Fuel injection system

ABSTRACT

A fuel injection system includes a substantial integration of various components, the fuel injection system including at least one fuel injector and at least one intake manifold, as well as a fuel supply channel, which are all surrounded by a plastic sheathing. The full integration of the fuel injectors into an induction pipe component made of plastic leads to the reduction or elimination of both electrical and hydraulic interfaces. Thus, only a compact component remains that is very simple to attach to a cylinder head of an internal combustion engine. Means for electrically contacting the fuel injectors (1), such as connector sockets, are also fully integrated in the plastic sheathing. This fuel injection system is especially suited for use in mixture-compressing internal combustion engines having externally supplied ignition.

FIELD OF THE INVENTION

The present invention related to a fuel injection system.

BACKGROUND INFORMATION

European Patent Application No. 0 139 122 describes a fuel injectionsystem that is able to be mounted on the cylinder head of an internalcombustion engine. This fuel injection system comprises a plurality ofintake lines that open into an elastic connecting tube element, whichisolates structure-borne noise and is configured, in turn, with a flangeon its cylinder-head side, a fixed connection to the cylinder head beingrealized with the flange. The elastic connecting tube element, which ispreferably made of an elastomeric plastic, thus, partially accommodatesthe intake lines and, in addition, has a sleeve-shaped mount for a fuelinjector (injection valve). The mount and connecting tube element formone piece which surrounds the fuel injector in its installed positionover nearly its entire extent. The fuel injection system, thus, has amultipart design, the complete fuel injector being installed in themount, which thus forms a holding means for it. In this context, themount is so configured that the outer contour of the fuel injector isessentially closely fitted.

Unexamined European Patent Application 0 501 612, the fuel injectionsystem having multipart intake manifolds with flanges at their ends forinterconnecting them. The intake manifolds are manufactured either fromaluminum or plastic and, in addition to their actual flow passages, haveseating areas for fuel injectors. These seating areas each essentiallysurround a fuel injector with a radial clearance, since, e.g., the fuelis supplied via the seating areas to fuel injectors configured as"side-feed" injectors. The fuel injectors are first introduced in theirfully assembled state into these seating areas. It is necessary for thefuel injector to be sealed off in the seating areas by at least twosealing rings.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a fuel injection systemwhose components are integrated to an extreme degree. This creates asimplified design over the prior art and thereby obtains a significantcost advantage. By fully integrating the injection valves on an intakemanifold or intake distributor made of plastic, both electrical, as wellas hydraulic interfaces of the fuel injection system are reduced or evenentirely eliminated. In addition, the advantageous elimination ofconnecting means and sealing means implies further savings in parts andthus in materials. The multiplicity of advantages obtained through fullintegration are listed, for example, as follows:

Elimination of the actual plastic extrusion coating around the fuelinjector.

Elimination of a component for supply fuel (e.g., fuel distributor).

Elimination of several connecting means (e.g., lock rings, screws andothers).

Elimination of various sealing means,(e.g., O-rings).

Elimination of several installation steps because of the one-partconfiguration.

It is especially advantageous to integrate the electrical lines (e.g.,)used for the common electrical contacting of the fuel injectors, intothe fuel distributor (e.g., used for supplying fuel to the fuelinjectors). Only one central connector is then needed for the externalelectrical connection of the fuel injection system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a partial section through a fuel injection system accordingto an embodiment of the present invention.

FIG. 2 shows a fuel injection system, configured for installation on thecylinder head of an internal combustion engine, with fuel injectorshaving individual connectors according to an embodiment of the presentinvention.

FIG. 3 shows a fuel injection system, configured for installation on thecylinder head of an internal combustion engine, having a centralconnector according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a partial section through a fuel injection system accordingto an embodiment of the present invention which comprises, inter alia,at least one fuel injector 1, the fuel injection system being used, inparticular, as part of a fuel injection system of mixture-compressinginternal combustion engines having externally supplied ignition. In FIG.1, only one fuel injector 1 is shown in section, in conjunction with anintake manifold 3 that is configured as a single induction pipe 1 andleads to a combustion chamber (not shown) of the internal combustionengine. As a rule, however, the fuel injection system will be used inconjunction with an MPI (multipoint injection), where, for example, eachcombustion chamber of the internal combustion engine is assigned its ownfuel injector 1. Thus, in an internal combustion engine having fourcombustion chambers (4-cylinder engine), for example, four intakemanifolds 3 extend in the direction of the combustion chambers, eachfuel injector 1 opening into an intake manifold 3. By way of intakemanifold 3 having, for example, a circular cross-section, intake air orrecirculated exhaust gas is made available to the internal combustionengine in the direction indicated by an arrow; the air quantity beingcontrolled by means of a throttle element (not shown) upstream from theopening of fuel injector 1 into intake manifold 3.

Well suited for service in the fuel injection system of the inventionare, for example, "top-feed" fuel injectors where the fuel is suppliedby way of the end facing away from the intake manifold. A fulldescription of the exemplary and simplified representation of fuelinjector 1 will not be given here, since such a fuel injector is alreadywell known from Unexamined German Application No. 43 25 842, which ishereby incorporated by reference, there being certain differences--ofcourse, in the matter of plastic extrusion coating because of the designof the fuel injection system according to the invention. Otherconstructions of already known fuel injectors may also be used in thefuel injection system.

the Fuel injector 1 is actuated in the known manner e.g.,electromagnetically. For that reason, fuel injector 1 has anelectromagnetic circuit comprising, inter alia, a solenoid coil 5, acore 6 used both as a fuel intake fitting and an inner pole, andcomprising an armature 7. Downstream from solenoid coil 5 extends avalve-seat carrier 8, which forms part of the housing of fuelinjector 1. Arranged in tubular valve-seat carrier 8 is a valve needle9, which at its upstream end is fixedly connected to armature 7 and, atits downstream end, is fixedly connected to a valve-closure member 10.The electromagnetic circuit is used to axially move valve needle 9 and,thus, to open the injector against the resistance of a return spring 11and to close it. Imperviously mounted in the end of valve-seat carrier 8facing away from core 6 is a valve-seat member 12, which has a fixedvalve seat, with which valve-closure member 10 cooperates, in turn.

The fuel to be spray-discharged is metered, e.g., through a pot-shapedspray-orifice plate 14-which is fixedly connected to valve-seat member12 and has at least one, e.g., four spray orifices formed by erosivemachining or punching. Disposed at the immediate downstream end ofvalve-seat carrier 8 is, for example, a protective cap 15. Solenoid coil5 is surrounded by at least one conductive element 16, configured as aclip and used as a ferromagnetic element, which at least partiallysurrounds solenoid coil 5 in the circumferential direction, abuts withits two ends on core 6 or on valve-seat carrier 8, and is securelyjoined thereto. Provision is made in a flow-through bore 18 of core 6,e.g., for a fuel filter 19 for filtering out fuel components that couldcause blockage, and for an adjustment sleeve 20 for adjusting theresilience of return spring 11.

The fuel injector 1 according to an embodiment of the present invention,is not, as previously known, surrounded by an injection-molded plastichousing to form a component that can be installed in a mount of a fuelinjection system, but rather is directly integrated into the fuelinjection system as described according to the present invention. Exceptfor a small downstream region 24 of fuel injector 1, fuel injector 1 iscompletely surrounded by plastic sheathing, the plastic sheathing 25being formed in one piece with intake manifolds 3 so as to form acompact fuel injection system and, thus, is also produced in a singleplastic injection-molding process. The plastic sheathing 25 may alsoinclude, for example, an integral injection molded electrical connector26 for each fuel injector 1.

In addition, a fuel distributor 28 is also provided directly within thefuel injection system, the fuel distributor also being directlyco-formed by plastic sheathing 25 of fuel injector 1. In this context,during the injection molding process, the injection-molding die includesan injection-molding core located immediately above the inflow-side endof fuel injector 1 and transversely to longitudinal valve axes 29 offuel injectors 1. Following removal of said core, a fuel supply channel30 is formed for fuel injectors 1 within plastic sheathing 25. The fuelsupply channel 30 that is open toward each flow-through bore 18 has, forexample, a circular cross-section, the plastic forming the wall of fuelsupply channel 30 being provided with a substantially constant wallthickness. The wall thickness of plastic sheathing 25 may vary along theaxial extent of fuel injector 1 to accommodate installationrequirements.

Fuel injectors 1 are adjusted prior to being extrusion-coated. In thiscontext, the insertion depth of valve-seat member 12 within thevalve-seat carrier 8 determines the magnitude of the lift of valveneedle 9. When solenoid coil 5 is not energized, one end position ofvalve needle 9 is determined by the position of valve-closure member 10on the seat of valve seat member 12; when solenoid coil 5 is excited,the other end position of valve needle 9 is determined by the fitting(e.g., seating ) of armature 7 on core 6. The spring tension of valveneedle 9 that is braced against return spring 11 is, as alreadymentioned, set by adjustment sleeve 20. Solenoid coil 5 is sealed fromfuel supply channel 30 by means, for example, of a plurality of ribs 32concentrically disposed around the periphery of core 6 near fueldistributor 28, the rings 32 forming a "labyrinth seal". Alternatively,an ordinary sealing ring installed on the periphery of core 6 could beco-extruded.

To economize on plastic, downstream area 24 of fuel injector 1 isconfigured as an exposed (open) area i.e., valve-seat carrier 8 is notenclosed by any plastic there. Rather, the area 24 protrudes into aside-opening 33 of intake manifold 3, which has, for example, a circularcross-section. In this context, fuel injector 1 is, for example, soaligned that the fuel to be spray-discharged impinges essentiallydirectly at an inlet valve (not shown) in the cylinder head of theinternal combustion engine. It is also conceivable to design fuelinjector 1 in a lengthened configuration and, by this means, allow it toproject fully through side opening 33, the injection end of fuelinjector 1 extending up to inside intake manifold 3, as indicated by thedotted lines.

FIGS. 2 and 3 show schematic exemplary embodiments of the fuel injectionsystem according to the present invention as a compact component forinstallation on the cylinder head of an internal combustion engine.Intake manifolds 3 terminate at a mounting flange 37 which, for example,has a plurality of openings 38 into which means for mounting the fuelinjection system to the cylinder head may be inserted. The individualfuel injectors 1 are, in the embodiment shown in FIG. 2, contactedseparately from one another, i.e., each fuel injector 1 has its own plugconnector 26 which may have the form represented in FIG. 1. Intakemanifolds 3 run as induction runners separately, at least in thedescribed fuel injection system, and together form an induction pipeassembly. Fuel distributor 28 extends with its inner fuel supply channel30 along all fuel injectors 1, rendering possible a simultaneoussupplying of fuel to all fuel injectors 1. At its one end, fueldistributor 28 has a connecting means 40. In this context, connectingmeans 40 is designed, for example, in the form of a connection pipefitting to which a fuel supply hose (not shown) can be attached, or itcan form a "quick-connector", which enables bayonet-type quickconnections to be achieved.

FIG. 3 shows an exemplary embodiment of the fuel injection systemaccording to the present invention where the electrical contacting ofindividual fuel injectors 1 is carried out by way of a contact bar 41that interconnects all fuel injectors 1. Contact bar 41, which isprovided directly at the time of injection molding of the fuel injectionsystem, and thus is completely extrusion-coated with plastic, has at itsone end a central connector 42 which, e.g., has a five-pin design givenfour fuel injectors 1 to be contacted. With every fuel injector 1, thenumber of electrical lines 43 provided in contact bar 41 decreases byone up to that fuel injector 1 which is the most remote from centralconnector 42 and to which two electrical lines 43 still lead. Contactbar 41 and fuel distributor 28 are not shown to scale in FIG. 3 and donot need to run separately next to one another or above and below oneanother. It is, rather, advantageous to integrate electrical lines 43directly in or on fuel distributor 28 so that there will only be oneplastic connecting piece running transversely to fuel injectors 1.

What is claimed is:
 1. A fuel injection system for an internalcombustion engine, comprising:at least one fuel injector coated with aplastic injection-molded coating; and at least one intake manifoldcooperating with the at least one fuel injector, wherein the plasticinjection-molded coating forms a fuel supply channel disposed adjacentto the at least one fuel injector, a wall of the at least one intakemanifold also being formed integral with the plastic injection-moldedcoating.
 2. The fuel injection system as defined by claim 1, wherein theplastic injection-molded coating includes a mounting flange at which theat least one intake manifold terminates, the mounting flange beingmounted to a cylinder head of the internal combustion engine.
 3. Thefuel injection system as defined by claim 1, wherein the at least onefuel injector includes at least two fuel injectors and the at least oneintake manifold includes at least two intake manifolds, each of the atleast two fuel injectors being assigned to a respective one of the atleast two intake manifolds, each of the at least two intake manifoldsbeing configured separately from another intake manifold.
 4. The fuelinjection system as defined by claim 1, wherein the at least one fuelinjector includes at least two fuel injectors, each fuel injector havinga longitudinal valve axis, the fuel supply channel running transverselyto the longitudinal valve axes of the at least two fuel injectors, thefuel supply channel and the plastic injection-molded coating forming thefuel supply channel forming a fuel distributor which proceeds directlyfrom the plastic injection-molded coating surrounding the at least twofuel injectors.
 5. The fuel injection system as defined by claim 1,wherein each of the at least one fuel injectors includes a unitaryelectrical connector integrally formed with the plastic injection-moldedcoating.
 6. The fuel injection system as defined by claim 1, whereineach of the at least two fuel injectors is connected to an electricalline of a contact bar, the contact bar being formed integral with theplastic injection-molded coating and terminating with a centralconnector, the electrical contacting of each of the at least one fuelinjectors being accomplished via the electrical line of the contact bar.7. The fuel injection system as defined by claim 4, wherein each of theat least two fuel injectors is connected to an electrical line of acontact bar, the contact bar being formed integral with the plasticinjection-molded coating and terminating with a central connector, theelectrical contacting of each of the at least one fuel injectors beingaccomplished via the electrical line of the contact bar and wherein theelectrical line is integrated in the fuel distributor.
 8. The fuelinjection system as defined by claim 1, wherein the at least one fuelinjector includes a core forming a fuel intake fitting and an inner polewhich forms an inflow-side end of the at least one fuel injector facingthe fuel-supply channel, an outer periphery of the core having aplurality of concentrically disposed, annular ribs enclosed by theplastic injection-molded coating.
 9. The fuel injection system asdefined by claim 10, wherein a downstream end region of the at least onefuel injector faces the at least one intake manifold, the downstream endregion being separated from the plastic injection-molded coating andextending into a side opening of the at least one intake manifold. 10.The fuel injection system as defined by claim 1, wherein an upper endregion of the at least one fuel injector receives fuel and issubstantially enclosed by the plastic injection-molded coating.
 11. Thefuel injection system as defined by claim 10, wherein the fuel supplychannel is situated at a top end of the upper end region of the at leastone fuel injector.
 12. The fuel injection system as defined by claim 1,wherein the at least one fuel injector is maintained in the plasticinjection-molded coating without using a lock ring.
 13. The fuelinjection system as defined by claim 1, wherein the at least one fuelinjector is a top-feed type injector.
 14. The fuel injection system asdefined by claim 1, wherein the plastic injection-molded coatingcontacts a substantial portion of the at least one fuel injector.